To assist medical patients having difficulty breathing, gases are supplied to and returned from the patients through multi-lumen breathing circuits. Because the gases are typically humidified and because of the difference between the atmospheric temperature and the temperature of the patient's breath, condensation commonly builds on the inside wall of the breathing circuits during use.
Various approaches have been implemented to reduce the condensation build up within the breathing circuits. In some known breathing circuits, collection points are provided within the breathing circuit tube for draining condensed liquid. In other known breathing circuits, a heating wire is included within the breathing circuit tube for maintaining or elevating the temperature of airflow or the temperature of the outer wall of the breathing circuit tube to reduce the formation of condensation. However, such heating wires may lead to ignition and subsequent fire, require their own power source, and are energy inefficient.
Currently, properties of the airflow in the multi-lumen breathing circuits are monitored by devices connected to the breathing circuits. For example, sensors can be included in ventilators connected to the proximal end of the breathing circuit tubes to monitor, for example, the temperature, rate, and/or gas content of the airflow. However, such measurements may not be accurate as the properties of the airflow may change along the axial length of the multi-lumen breathing circuits. For example, the temperature and rate of the airflow near the distal end of the multi-lumen breathing circuit in communication with the patient may differ from the temperature and rate of the airflow near the proximal end of the multi-lumen breathing circuit in communication with the measuring device. The inaccurate measurements may lead to lower quality care of the patients.
Therefore, a need exists to more effectively control the temperature and/or humidity of airflow, and monitor airflow properties at various points within a multi-lumen breathing circuit.